Microscopic Observation Drug Susceptibility Assay for Rapid Diagnosis of Lymph Node Tuberculosis and Detection of Drug Resistance

Clinical Characteristics and Treatment Outcomes of Definitive Versus Standard Anti-Tuberculosis Therapy in Patients with Tuberculous Lymphadenitis

Although it is necessary to culture Mycobacterium tuberculosis from tuberculous lymphadenitis (TBL) patients for definitive therapy, based on the drug-sensitivity test (DST), substantial cases remain culture-negative. Limited data are available regarding the treatment outcomes after standard anti-tuberculosis therapy in culture-negative TBL. The aim of this study was to compare the recurrence rates between definitive anti-tuberculosis therapy, based on DST and standard anti-tuberculosis therapy in culture-negative TBL. A multicenter retrospective cohort study was performed from 2011 to 2015 in South Korea. The study population was divided into two groups according to treatment type. A total of 234 patients with TBL were analyzed, who were treated with definitive (84 patients) and standard anti-tuberculosis (150 patients) therapy, respectively. During a 28.0 (24.0–43.0) month follow-up period, nine cases (3.8%) had recurrence of TB after treatment completion. The recurrence rate was not significantly different between the two groups (2/84, 2.4% in definitive anti-tuberculosis therapy group versus 7/150, 4.7% in standard anti-tuberculosis therapy group, p = 0.526). The recurrence in all nine cases was diagnosed as clinical recurrence rather than microbiological recurrence. Therefore, culture-negative TBL can be treated with standard anti-TB medication, although DST is not available but clinically stable after initiation of treatment.

Novel fluoronucleoside analog NCC inhibits lamivudine-resistant hepatitis B virus in a hepatocyte model

Antiviral drug resistance is the most important factor contributing to treatment failure using nucleos(t)ide analogs such as lamivudine for chronic infection with hepatitis B virus (HBV). Development of a system supporting efficient replication of clinically resistant HBV strains is imperative, and new antiviral drugs are needed urgently to prevent selection of drug-resistant HBV mutants. A novel fluorinated cytidine analog, NCC (N-cyclopropyl-4′-azido-2′-deoxy-2′-fluoro-β-d-cytidine), was recently shown to strongly inhibit human HBV in vitro and in vivo. This study was designed to evaluate the antiviral activity of NCC against lamivudine-resistant HBV. We generated a stable cell line encoding the major pattern of lamivudine-resistant mutations rtL180M/M204V and designated it “HepG2.RL1”. Immuno-transmission electron microscopic examination and enzyme-linked immunosorbent assay were used to detect secretion of HBV-specific particles and antigens. Quantification of extracellular DNA and intracellular DNA of HepG2.RL1 cells by quantitative real-time polymerase chain reaction revealed >625-fold and >5556-fold increases in the 50% inhibitory concentration of lamivudine, respectively, compared with that for the wild-type virus. The results showed that NCC inhibited DNA replication and HBeAg production in wild-type or lamivudine-resistant HBV in a dose-dependent manner. In conclusion, screening for antiviral compounds active against lamivudine-resistant HBV can be carried out with relative ease using hepG2.RL1 cells. NCC is a potential antiviral agent against wild-type HBV and clinical lamivudine-resistant HBV and deserves evaluation for the treatment of HBV infection.

Lymph nodes are sites of prolonged bacterial persistence during Mycobacterium tuberculosis infection in macaques

Tuberculosis is commonly considered a chronic lung disease, however, extrapulmonary infection can occur in any organ. Even though lymph nodes (LN) are among the most common sites of extrapulmonary Mycobacterium tuberculosis (Mtb) infection, and thoracic LNs are frequently infected in humans, bacterial dynamics and the effect of Mtb infection in LN structure and function is relatively unstudied. We surveyed thoracic LNs from Mtb-infected cynomolgus and rhesus macaques analyzing PET CT scans, bacterial burden, LN structure and immune function. FDG avidity correlated with the presence of live bacteria in LNs at necropsy. Lymph nodes have different trajectories (increasing, maintaining, decreasing in PET activity over time) even within the same animal. Rhesus macaques are more susceptible to Mtb infection than cynomolgus macaques and this is in part due to more extensive LN pathology. Here, we show that Mtb grows to the same level in cynomolgus and rhesus macaque LNs, however, cynomolgus macaques control Mtb at later time points post-infection while rhesus macaques do not. Notably, compared to lung granulomas, LNs are generally poor at killing Mtb, even with drug treatment. Granulomas that form in LNs lack B cell-rich tertiary lymphoid structures, disrupt LN structure by pushing out T cells and B cells, introduce large numbers of macrophages that can serve as niches for Mtb, and destroy normal vasculature. Our data support that LNs are not only sites of antigen presentation and immune activation during infection, but also serve as important sites for persistence of significant numbers of Mtb bacilli.

Since tuberculosis is commonly considered a chronic lung disease, most studies in tuberculosis focus on the lungs while lymph nodes are almost always depicted only as sites of antigen presentation and immune activation. However, lymph nodes are among the most frequently infected sites of Mycobacterium tuberculosis (Mtb) aside from the lungs. The effect of Mtb infection and how lymph nodes respond to Mtb infection is currently unknown. To investigate this, we examined the lymph nodes of two macaque species, cynomolgus and rhesus macaques, at different time points after Mtb infection. We found that overall lymph nodes are not effective killers of Mtb; the lymph nodes of rhesus macaques being less effective at killing Mtb than cynomolgus macaques. Mtb infection also resulted in the destruction of the lymph node structure and this was associated with increased bacterial burden. After a short course of anti-TB drug therapy, the reduction in bacterial burden was lower in lymph nodes compared to lung granulomas. Our data show that aside from being sites of antigen presentation and immune activation, lymph nodes are also niches of Mtb growth and persistence.

Histological Examination in Obtaining a Diagnosis in Patients with Lymphadenopathy in Lima, Peru

The differential diagnosis for lymphadenopathy is wide and clinical presentations overlap, making obtaining an accurate diagnosis challenging. We sought to characterize the clinical and radiological characteristics, histological findings, and diagnoses for a cohort of patients with lymphadenopathy of unknown etiology. 121 Peruvian adults with lymphadenopathy underwent lymph node biopsy for microbiological and histopathological evaluation. Mean patient age was 41 years (Interquartile Range 26–52), 56% were males, and 39% were HIV positive. Patients reported fever (31%), weight loss (23%), and headache (22%); HIV infection was associated with fever (P < 0.05) and gastrointestinal symptoms (P < 0.05). Abnormalities were reported in 40% of chest X-rays (N = 101). Physicians suspected TB in 92 patients (76%), lymphoma in 19 patients (16%), and other malignancy in seven patients (5.8%). Histological diagnoses (N = 117) included tuberculosis (34%), hyperplasia (27%), lymphoma (13%), and nonlymphoma malignancy (14%). Hyperplasia was more common (P < 0.001) and lymphoma less common (P = 0.005) among HIV-positive than HIV-negative patients. There was a trend toward reduced frequency of caseous necrosis in samples from HIV-positive than HIV-negative TB patients (67 versus 93%, P = 0.055). The spectrum of diagnoses was broad, and clinical and radiological features correlated poorly with diagnosis. On the basis of clinical features, physicians over-diagnosed TB, and under-diagnosed malignancy. Although this may not be inappropriate in resource-limited settings where TB is the most frequent easily treatable cause of lymphadenopathy, diagnostic delays can be detrimental to patients with malignancy. It is important that patients with lymphadenopathy undergo a full diagnostic work-up including sampling for histological evaluation to obtain an accurate diagnosis.

Tuberculous Lymphadenitis and Parotitis

Tuberculous lymphadenitis is the most common extrapulmonary manifestation of disseminated tuberculosis (TB). It is considered to be the local manifestation of the systemic disease that has disseminated to local lymph nodes, but a high index of suspicion is needed for the diagnosis, because there are several infectious and noninfectious diseases that can mimic the same clinical picture. In recent years, different diagnostic methods have been introduced, including fine-needle aspiration cytology, which has emerged as a simple outpatient diagnostic procedure that replaced the complete excisional node biopsy, and a number of molecular methods which have greatly improved diagnostic accuracy. This chapter covers the most actual knowledge in terms of epidemiology, clinical manifestations, pathogenesis, and treatment and emphasizes current trends in diagnosis of tuberculous lymphadenitis. TB parotid gland involvement is extremely rare, even in countries in which TB is endemic. Because of the clinical similarity, parotid malignancy and other forms of parotid inflammatory disease always take priority over the rarely encountered TB parotitis when it comes to differential diagnosis. As a result, clinicians often fail to make a timely diagnosis of TB parotitis when facing a patient with a slowly growing parotid lump. This chapter highlights the most important features of this uncommon disease.